Synthetic Molecular Gear Based on Double-Decker Porphyrin Complexes

New rotary molecular machines (1 and 2) were synthetically constructed from two distinct porphyrin-based rotors, a cerium(IV) bis(porphyrinate)s double-decker (CeDD) and a porphyrinatorhodium(III)-based rotor. These rotors are adjacently mounted on rotational axes aligned to near vertical as resembling the bevel-gear-shaped structure. Structural study using NMR analysis reveals that these distinct rotors are connected through a coordination bond between rhodium(III) and a pyridyl group. At temperature from 193 to 393 K, each rotor represents rotational motion driven by heat fluctuation without decomposition into the corresponding precursors in dichloromethane-d ₂ and tetrachloroethane-d ₄. Importantly, the mechanical interaction between the teeth of these rotors is strongly dependent on the central metal atom in a DD rotor and the teeth structure in a porphyrinatorhodium(III)-based rotor. Understanding such relationship between the chemical structures and mechanical interaction is of importance for generating cooperative motion in the hybrid machinery system.     

Runoff Analysis for a Small Watershed of Tono Area Japan by Back Propagation Artificial Neural Network with Seasonal Data

The rainfall runoff (R-R) process was studied for two small sub-basins having different sizes in a mountainous catchment of Tono area Japan. The runoff and other meterological data have been collected in this catchment for the last 14 years. The major objective of this study was to construct numerical models for these sub-basins to predict runoff after 1/2 and 1 h. The effects of season and the size of the catchment on R-R process were also investigated. The hydrogeological conditions of the catchment were studied prior to the analyses. The data obtained for summer (rainy) and winter (dry) seasons were treated separately in order to study the seasonal effects on the model development. The back propagation artificial neural network technique (BPANN) and the multivariate autoregressive and moving average models (ARMA) were adopted for the analysis. It was found that for very small catchments the seasonal effects are dominant and therefore separate models should be developed for each season to obtain better forecasting estimates. It was also found that the predictions by BPANN models were better than multivariate ARMA models for intense rains having complex R-R relationships in summer. On the other hand, both the modelling techniques yielded almost similar results for smaller rains in winter. It was also found clearly that the accuracy of prediction decreased with the increase of the time period for prediction.     

Dual-metal gate CMOS technology with ultrathin silicon nitride gatedielectric

We report the first demonstration of a dual-metal gate complementary metal oxide semiconductor (CMOS) technology using titanium (Ti) and molybdenum (Mo) as the gate electrodes for the N-metal oxide semiconductor field effect transistors (N-MOSFETs) and P-metal oxide semiconductor field effect transistors (P-MOSFETs), respectively. The gate dielectric stack consists of a silicon oxy-nitride interfacial layer and a silicon nitride (Si₃N₄) dielectric layer formed by a rapid-thermal chemical vapor deposition (RTCVD) process. C-V characteristics show negligible gate depletion. Carrier mobilities comparable to that predicted by the universal mobility model for silicon dioxide (SiO₂) are observed     

Geometry Dependence of Magnetization Reversal in Nanocomposite Alloys

The geometrical optimization of aligned hard-soft permanent-magnet nanocomposites is investigated by model calculations. Considered criteria are the shapes of the soft and c-axis-aligned hard phases, the packing fraction of the soft phase, and magnetostatic interactions. Taking into account that the energy product is enhanced via the volume fraction of the soft phase, subject to maintaining coercivity, we find that the best structures are soft-magnetic cubes as well as long rods with a square cross section. Comparing embedded soft cubes with embedded soft spheres of the same size, our nucleation-field analysis shows that the volume fraction of the soft phase is enhanced by 91%, with a coercivity reduction of only 25%. Magnetostatic interactions often but not always deteriorate the permanent-magnet performance, as exemplified by the example of MnBi:FeCo bilayers and multilayers.     

Pd20Pt20Cu20Ni20P20 high-entropy alloy as a bulk metallic glass in the centimeter

A Pd₂₀Pt₂₀Cu₂₀Ni₂₀P₂₀ bulk metallic glass (BMG) with a high-entropy (HE) alloy composition and a maximum diameter of 10 mm was fabricated by fluxed water quenching. The system and composition of the Pd₂₀Pt₂₀Cu₂₀Ni₂₀P₂₀ alloy were determined from a prototype ternary Pd₄₀Ni₄₀P₂₀ BMG in accordance with two strategic alloy designs of (1) HE alloy defined by an equi-atomic alloy with five or more elements and (2) exchangeability of the constituent elements with a similar chemical nature in the periodic table. Pd₂₀Pt₂₀Cu₂₀Ni₂₀P₂₀ HE-BMG had a supercooled liquid range of 65 K and a reduced glass transition temperature of 0.71. Successful formation of Pd₂₀Pt₂₀Cu₂₀Ni₂₀P₂₀ HE-BMG is significant to develop new alloys for HE alloys and BMGs.     

Current Pumping from Spin Dynamics

We show theoretically that charge and spin currents arise from spin dynamics in the presence of the spin–orbit interaction. The dominant calculation is the inverse spin Hall effect, namely the spin current pumped from precession of local spins is converted into the charge current by the spin–orbit interaction. The conversion mechanism is explained based on the conservation laws of charge and spin.     

LD抽运的Cr4+∶YAG被动调Q Nd∶YAG激光器

研究了不同谐振腔下不同透射率的Cr4 + ∶YAG调Q的激光输出特性。采用透射率为 82 %的Cr4 + ∶YAG ,在抽运功率 1 1W时 ,激光重复频率小于 3kHz,单脉冲能量达 2 0 μJ ,可以作为微脉冲激光雷达的发射光源。分析和比较了实验结果和理论计算 ,两者吻合较好     

BSCCO Superconductors: Hole-Like Fermi Surface and Doping Dependence of the Gap Function

We use the gradient of the energy-integrated angle resolved photoemission (ARPES) intensity in order to define precisely the Fermi surface (FS) in BSCCO superconductors. We show that, independent of the photon energy, the FS is a hole barrel centered at (, ). Then, the superconducting gap along the FS is precisely determined from ARPES measurements on overdoped and underdoped samples of Bi2212. As the doping decreases, the maximum gap increases, but the slope of the gap near the nodes decreases. Though consistent with d-wave symmetry, the gap with underdoping cannot be fit by the simple cos(k _x) – cos(k _y) form. A comparison of our ARPES results with available penetration depth data indicates that the renormalization of the linear T suppression of the superfluid density at low temperatures due to quasiparticle excitations around the d-wave nodes is large and doping dependent.     

Low Frequency Susceptibility of High-Density bcc Solid 3He in the Paramagnetic and Nuclear-Ordered States

We have measured the AC magnetic susceptibility and static magnetization of high-density bcc solid ³ He through the nuclear-ordering transition. The susceptibility in the paramagnetic state strongly depends on the frequency of the measuring field. Near the transition temperature a sharp peak in the real part of the AC susceptibility and an abrupt depression in the imaginary part are observed. The transition temperature indicated by the AC susceptibility is higher than that derived from static magnetization. We analyzed the new behavior in the susceptibility in terms of the spin relaxation between the Zeeman system and the exchange system. The relaxation time in the energy flow in the two systems is in the range of milliseconds in the paramagnetic state, and decreases drastically by two orders of magnitude in the ordered state. The relaxation time in the paramagnetic state is interpreted as due to exchange narrowing, while in the ordered state is explained to be the drift time of the spin wave limited by the size of the sample grown in the pores of the sintered silver. The ordering temperature is given as a function of molar volume in the entire range of the bcc phase.     

New Arabidopsis cue mutants suggest a close connection between plastid- and phytochrome regulation of nuclear gene expression

We searched for new components that are involved in the positive regulation of nuclear gene expression by light by extending a screen for Arabidopsis cue (chlorophyll a/b-binding [CAB] protein-underexpressed) mutants (H.-M. Li, K. Culligan, R.A. Dixon, J. Chory [1995] Plant Cell 7: 1599-1610). cue mutants display reduced expression of the CAB3 gene, which encodes light-harvesting chlorophyll protein, the main chloroplast antenna. The new mutants can be divided into (a) phytochrome-deficient mutants (hy1 and phyB), (b) virescent or delayed-greening mutants (cue3, cue6, and cue8), and (c) uniformly pale mutants (cue4 and cue9). For each of the mutants, the reduction in CAB expression correlates with the visible phenotype, defective chloroplast development, and reduced abundance of the light-harvesting chlorophyll protein. Levels of protochlorophyllide oxidoreductase (POR) were reduced to varying degrees in etiolated mutant seedlings. In the dark, whereas the virescent mutants displayed reduced CAB expression and the lowest levels of POR protein, the other mutants expressed CAB and accumulated POR at near wild-type levels. All of the mutants, with the exception of cue6, were compromised in their ability to derepress CAB expression in response to phytochrome activation. Based on these results, we propose that the previously postulated plastid-derived signal is closely involved in the pathway through which phytochrome regulates the expression of nuclear genes encoding plastid proteins.